Black screen. When pushing button the get red lightning bolt and time briefly
Black screen. When push button briefly get time and red lightning bolt. How do I restart watch?
Hi
Apple Watch displays the time and a red lightning bolt - and cannot be used for any other functions - when it has entered into Power Reserve mode, which happens automatically when the battery reaches a low charge level (and can also be enabled manually).
To resume normal function, you will need to restart your watch: press and hold the side button until you see the Apple logo.
However, you may need to charge your watch before it can be restarted.
More information (scroll down to the heading "Use Power Reserve"):
Check your battery and charge your Apple Watch - Apple Support